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36
Among the cases included in the first period there were 8 deaths, 2 males and
6 females ; in the second period there were 3 deaths, all females.
The sudden appearance of the prevalence pointed to the probability that water
or some foodstuff was at fault. Inquiries as to a possible source of infection yielded
no result as regards either water or any particular kind of food—save milk, ice-cream,
shellfish and fish ; these four foods will be considered in turn, the two first, milk and
ice-cream, being taken together, inasmuch as milk forms one of the constituents of
ice-cream.
The question
of milk, or
milk and icecream,
as the
possible
vehicle of
infection.
It was apparent, from enquiries made on behalf of the health department of
Bethnal-green soon after the occurrence of the early cases, that the majority of the
sufferers had, either occasionally, or in some instances day by day, consumed milk
supplied from a particular cowshed; suspicion naturally fell upon this milk supply,
which will henceforward be referred to as source X.
Much time and attention were given to study of the business of the milk vendor
in question. The milk premises themselves and the cows were examined by officers
of the Council and of the borough council, and bacteriological tests (to be immediately
referred to) were applied to the roundsmen and milkers at the instance of the medical
officer of health of Bethnal-green. In addition to the milk from his own cows,
(there were in all 45 milch cows), a small quantity of milk was obtained by the milk
vendor from a neighbouring firm of wholesale dairymen. Milk from this latter source
was supplied in considerable quantity outside the affected area, and no cases of
illness were attributable to it; it can thus be dismissed from further consideration.
The blood of 13 persons resident on or employed at the milkshop premises was
examined; in the cases of a roundsman and a cowman the blood serum agglutinated
B. Typhosus in 1/25 and 1/50 dilutions respectively. Dr. Oates reports:
"After exhaustive examination of the excreta of these two men there was
no evidence forthcoming that they were carriers of typhoid infection." The milk
vendor himself was attacked by the disease, but as his symptoms did not commence
until four cases among his customers had already occurred, it is difficult to assume
that he can have infected the milk. Suspicion was directed to a son of the milk
vendor who was suffering from empyema, following upon pneumonia in July; there
was, however, no bacteriological evidence forthcoming, after full enquiry, to show
that this boy was a typhoid carrier.
Certain considerations militated strongly against acceptance of a milk origin of
the outbreak. Previous enquiries have shown that in milk outbreaks of disease
women and young children are specially implicated ; whereas here these phenomena
were not marked so far as the cases occurring in the first four weeks, forming the
main prevalence, were concerned. In milk outbreaks, moreover, multiple house
attacks are common; here, in the main prevalence, they were relatively rare. Again,
in milk outbreaks those who buy considerable quantities of milk suffer more than
those who only purchase small quantities; in Bethnal-green this was not found to be
the case.
Each case has been carefully classified according to whether—
(a) Milk from source X was the sole supply of fresh milk.
(b) Milk from source X was occasionally consumed.
(c) Milk from source X had not been obtained at any time.
Of the 74 cases, constituting the special prevalence—in which the onset of illness
dated from 12th September to 7th November—32 fall into class (a), 20 into class (b)
and 22 into class (c). As regards those in class (a), in one instance it was specially
stated that the milk was " sterilised," and in another that milk was " never taken
except in tea."
In eight of the 74 cases, however, there was some question as to the correctness
of the diagnosis of typhoid fever. Class (a) included four of these, class (b) one and
class (c) three. Thus of the 66 cases in which the diagnosis of typhoid fever was
confirmed 30 per cent, did not have milk from source X and 25 per cent, had the
milk only occasionally. Dr. Oates, classifying the cases as " primary " and